Chromatographic And Electrophoretic Separation Media And Apparatus

Abstract

The invention provides improved separation media for use in chromatography and electrophoresis, or for the selective absorption of certain components of a sample mixture, especially in a preliminary stage of an analysis. Improved media according to the invention comprises first particles capable or retaining one or more of the components of a sample mixture and second particles selected to have a higher thermal conductivity than the first particles, so that the thermal conductivity of the media is higher than that of media comprising the first particles alone. The media may be incorporated in packed or capillary columns for chromatography (especially nanoflow HPLC) or for capillary electrophoresis, or may be coated on a substrate. Particular embodiments of the media may comprise mixtures of first particles comprising siliceous polymers, second particles of gold, diamond or graphite. Chromatographic columns and apparatus incorporating them are also disclosed.

1 . Separation media for use in the chromatographic separation of a sample mixture, said separation media comprising first particles of a first material and second particles of a second material, said first particles being capable of at least temporarily retaining at least one of component of a sample mixture, and said second material being selected to have a higher thermal conductivity than said first material. 
     
     
         2 . Separation media as claimed in  claim 1  wherein said first material is selected from the group comprising: silica, glass, graphite, zirconia (zirconium oxide), organic polymers, alumina (aluminium oxide), gels, and siliceous polymers. 
     
     
         3 . Separation media as claimed in  claim 1  wherein first material is selected from the group comprising cross-linked styrenes, methacrylate polymers and polyamides. 
     
     
         4 . Separation media as claimed in  claim 1  wherein said first material comprises a polyacrylamide gel. 
     
     
         5 . Separation media as claimed in  claim 1  wherein said first material comprises a siliceous polymer represented by the formula SiO 2 /[R 2   p R 4   q SiO t ] n , where R 2  and R 4  are independently C 1 -C 18  aliphatic or aromatic moieties, p+q=0, 1 or 2, provided that t=1.5 if p+q=1 and t=1 if p+q=2, and n is a number between 0.03 and 1. 
     
     
         6 . Separation media as claimed in  claim 1  wherein said first material comprises a siliceous polymers represented by the formula SiO 2 /[R 6  (R 2   r SiO t ) m ] n , where R 2  is C 1 -C 18  aliphatic or aromatic moiety, R 6  is a substituted or unsubstituted C 1 -C 18  alkylene, alkynylene, or arylene moiety bridging two or more silicon atoms, r=0 or 1, provided that t=1.5 if r=0 and t=1 if r=1, m is an integer ≧2, and n is a number between 0.03 and 1. 
     
     
         7 . Separation media as claimed in  claim 1  wherein said first material comprises a siliceous polymer having a structure represented by: 
       
         
           
           
               
               
           
         
         The open valences above are terminal hydrogen, or alkylene, alkynylene, or arylene groups or are bonded to further subgroups of the structure depicted. As used above, x is an integer from 1 to infinity. 
       
     
     
         8 . Separation media as claimed in  claim 1  wherein said first material comprises a siliceous polymer having a structure represented by: 
       
         
           
           
               
               
           
         
         The open valences above are terminal hydrogen, or alkylene, alkynylene, or arylene groups or are bonded to further subgroups of the structure depicted. As used above, y is an integer from 1 to infinity. 
       
     
     
         9 . Separation media as claimed in  claim 2  wherein said first particles comprise surfaces modified with functional moieties selected from the group comprising alkyl moieties, phenyl moieties, aryl moieties, or carbamate moieties. 
     
     
         10 . Separation media as claimed in  claim 3  wherein said first particles comprise surfaces modified with functional moieties selected from the group comprising alkyl moieties, phenyl moieties, aryl moieties, or carbamate moieties. 
     
     
         11 . Separation media as claimed in  claim 5  wherein said first particles comprise surfaces modified with functional moieties selected from the group comprising alkyl moieties, phenyl moieties, aryl moieties, and carbamate moieties. 
     
     
         12 . Separation media as claimed in  claim 6  wherein said first particles comprise surfaces modified with functional moieties selected from the group comprising alkyl moieties, phenyl moieties, aryl moieties, and carbamate moieties. 
     
     
         13 . Separation media as darned in  claim 1  wherein said second material has a thermal conductivity in a range selected from the group comprising 0.1-0.5 W·cm −1 ·° K −1 , 0.5-1.0 W·cm −1 ·° K −1 , 1.0-10.0 W·cm −1 ·° K −1 , and 10-50 W·cm −1 ·K −1 . 
     
     
         14 . Separation media as claimed in  claim 1  wherein said second material is selected from the group comprising silver, copper, aluminium, gold, tungsten, molybdenum, alumina, aluminium nitride, titanium carbide, silicon carbide, zirconium oxide, diamond, and graphite. 
     
     
         15 . Separation media as claimed in  claim 1  wherein the proportion of second particles comprised in said separation media is between 1% and 25%. 
     
     
         16 . Separation media as claimed in  claim 1  wherein the proportion of second particles comprised in said separation media is between 5% and 20%. 
     
     
         17 . Separation media as claimed in  claim 1  wherein the proportion of second particles comprised in said separation media is approximately 10%. 
     
     
         18 . Separation media as claimed in  claim 5  wherein said second material is selected from the group comprising gold, diamond and graphite, and said first particles comprise surfaces modified with a functional moiety selected from the group comprising alkyl moieties, phenyl moieties, aryl moieties, and carbamate moieties. 
     
     
         19 . Separation media as claimed in  claim 6  wherein said second material is selected from the group comprising gold, diamond, and graphite, and said first particles comprise surfaces modified with a functional moiety selected from the group comprising alkyl moieties, phenyl moieties, aryl moieties, and carbamate moieties. 
     
     
         20 . Apparatus for the chromatographic separation of a sample mixture comprising a tubular member having an inlet through which a fluid may enter and an outlet through which fluid may leave, said tubular member having an interior space disposed between said inlet and said outlet, wherein there is disposed in said interior space separation media comprising first particles of a first material and second particles of a second material, said first particles being capable of at least temporarily retaining at least one component of a said sample mixture and said second material being selected to have a higher thermal conductivity than said first material. 
     
     
         21 . Apparatus as claimed in  claim 20  wherein said first material is selected from the group comprising silica, glass, graphite, zirconia (zirconium oxide), organic polymers, alumina (aluminium oxide), gels, and siliceous polymers. 
     
     
         22 . Apparatus as claimed in  claim 20  wherein said second material is selected from the group comprising silver, copper, aluminium, gold, tungsten, molybdenum, alumina, aluminium nitride, titanium carbide, silicon carbide, zirconium oxide, diamond and graphite. 
     
     
         23 . Apparatus as claimed in  claim 20  wherein said first material comprise a siliceous polymer represented by the formula SiO 2 /[R 2   p R 4   q Sio t ] n , where R 2  and R 4  are independently C 1 -C 18  aliphatic or aromatic moieties, p+q=0, 1 or 2, provided that t=1.5 if p+q=1 and t=1 if p+q=2, and n is a number between 0.03 and 1. 
     
     
         24 . Apparatus as claimed in  claim 20  wherein said first material comprises a siliceous polymer represented by the formula SiO 2 /[R 6  (R 2   r SiO t ) m ] n , where R 2  is C 1 -C 18  aliphatic or aromatic moiety, R 6  is a substituted or unsubstituted C 1 -C 18  alkylene, alkynylene, or arylene moiety bridging two or more silicon atoms, r=0 or 1, provided that t=1.5 if r=0 and t=1 if r=1, m is an integer ≧2, and n is a number between 0.03 and 1. 
     
     
         25 . Apparatus as claimed in  claim 23  wherein said second material is selected from the group comprising gold, diamond, and graphite. 
     
     
         26 . Apparatus as claimed in  claim 24  wherein said second material is selected from the group comprising gold, diamond, and graphite. 
     
     
         27 . Apparatus for selectively absorbing at least one component of a sample mixture on separation media, said apparatus comprising means for applying a fluid comprising a said sample mixture to said separation media, wherein said separation media comprises first particles of a first material and second particles of a second material, said first particles being capable of at least temporarily retaining at least one component of a said sample mixture and said second material being selected to have a higher thermal conductivity than said first material. 
     
     
         28 . Apparatus as claimed in  claim 27  wherein said first material is selected from the group comprising silica, glass, graphite, zirconia (zirconium oxide), organic polymers, alumina (aluminium oxide), gels, and siliceous polymers. 
     
     
         29 . Apparatus as claimed in  claim 27  wherein said second material is selected from the group comprising silver, copper, aluminium, gold, tungsten, molybdenum, alumina, aluminium nitride, titanium carbide, silicon carbide, zirconium oxide, diamond, and graphite. 
     
     
         30 . Apparatus as claimed in  claim 27  wherein said first material comprise a siliceous polymer represented by the formula SiO 2 /[R 2   p R 4   q SiO t ] n , where R 2  and R 4  are independently C 1 -C 18  aliphatic or aromatic moieties, p+q=0, 1 or 2, provided that t=1.5 if p+q=1 and t=1 if p+q=2, and n is a number between 0.03 and 1. 
     
     
         31 . Apparatus as claimed in  claim 27  wherein said first material comprises a siliceous polymer represented by the formula SiO 2 /[R 6  (R 2   r SiO t ) m ] n , where R 2  is C 1 -C 18  aliphatic or aromatic moiety, R 6  is a substituted or unsubstituted C1-C 18  alkylene, alkynylene, or arylene moiety bridging two or more silicon atoms, r=0 or 1, provided that t=1.5 if r=0 and t=1 if r=1, m is an integer ≧2, and n is a number between 0.03 and 1. 
     
     
         32 . Apparatus as claimed in  claim 30  wherein said second material is selected from the group comprising gold, diamond and graphite. 
     
     
         33 . Apparatus as claimed in  claim 31  wherein said second material is selected from the group comprising gold, diamond and graphite. 
     
     
         34 . Apparatus as claimed in  claim 27  wherein said first material comprises is selected from the group comprising cross-linked styrenes, methacrylate polymers, polyamides and polyacrylamide gels. 
     
     
         35 . Apparatus as claimed in  claim 34  wherein said second material is selected from the group comprising silver, copper, aluminium, gold, tungsten, molybdenum, alumina, aluminium nitride, titanium carbide, silicon carbide, zirconium oxide, diamond and graphite. 
     
     
         36 . Apparatus as claimed in  claim 20  for the analysis of a sample mixture comprising one or more constituents, further comprising a high-pressure pump, a sample injection device, and a detector responsive to at least one constituent of a said sample mixture. 
     
     
         37 . Apparatus as claimed in  claim 36  wherein said first material is selected from the group comprising silica, glass, graphite, zirconia (zirconium oxide), organic polymers, alumina (aluminium oxide), gels, and siliceous polymers, and said second material is selected from the group comprising silver, copper, aluminium, gold, tungsten, molybdenum, alumina, aluminium nitride, titanium carbide, silicon carbide, zirconium oxide, diamond and graphite. 
     
     
         38 . Apparatus as claimed in  claim 20  wherein said tubular member is disposed between reservoirs, each containing a buffer solution, and a high-voltage power supply for applying a potential difference between said reservoirs so that said buffer solution flows through said tubular member. 
     
     
         39 . Apparatus as claimed in  claim 38  wherein said first material is selected from the group comprising silica, glass, graphite, zirconia (zirconium oxide), organic polymers, alumina (aluminium oxide), gels, and siliceous polymers, and said second material is selected from the group comprising silver, copper, aluminium, gold, tungsten, molybdenum, alumina, aluminium nitride, titanium carbide, silicon carbide, zirconium oxide, diamond and graphite. 
     
     
         40 . Apparatus as claimed in  claim 27  further comprising a high-voltage power supply and wherein said separation media is disposed on a substrate, and said high-voltage power supply provides a potential difference across said substrate, whereby components of a said sample mixture may be separated by electrophoresis. 
     
     
         41 . Apparatus as claimed in  claim 40  wherein said first material is selected from the group comprising silica, glass, graphite, zirconia (zirconium oxide), organic polymers, alumina (aluminium oxide), gels, and siliceous polymers, and said second material is selected from the group comprising silver, copper, aluminium, gold, tungsten, molybdenum, alumina, aluminium nitride, titanium carbide, silicon carbide, zirconium oxide, diamond and graphite. 
     
     
         42 . Apparatus as claimed in  claim 22  further comprising means for minimizing any temperature gradient in an axial direction along said tubular member. 
     
     
         43 . Apparatus as claimed in  claim 42  wherein said means for minimizing any temperature gradient comprises a jacket surrounding said tubular member and fitted with at least one heater and at least one temperature sensor, and a temperature controller responsive to signals from said at least one temperature sensor, said temperature controller for supplying and controlling power to said at least one heater. 
     
     
         44 . Apparatus as claimed in  claim 42  wherein said means for minimizing any temperature gradient comprises a jacket surrounding said tubular member and fitted with at least one cooling device and at least one temperature sensor, and a temperature controller responsive to signals from said at least one temperature sensor, said temperature controller for supplying and controlling power to said at least one cooling device. 
     
     
         45 . Apparatus as claimed in  claim 44  wherein said cooling device comprises a Peltier effect device. 
     
     
         46 . Apparatus as claimed in  claim 42  wherein said tubular member is immersed in a water bath. 
     
     
         47 . Apparatus as claimed in  claim 42  wherein said tubular member is subjected to a flow of air. 
     
     
         48 . An apparatus for the chromatographic separation of a sample mixture comprising a tubular member having an inlet through which a fluid may enter and an outlet through which fluid may leave, said tubular member having an interior space disposed between said inlet and said outlet, wherein there is disposed in said interior space separation media comprising first particles of a first material and second particles of a second material, said first particles being capable of at least temporarily retaining at least one component of a said sample mixture and said second material being selected to have a higher thermal conductivity at least ten time greater than said first material and said second material is present in a concentration of between 1 and twenty-five percent by volume, wherein said first material is selected from the group consisting of silica, glass, graphite, zirconia (zirconium oxide), organic polymers, alumina (aluminium oxide), gels, and siliceous polymers and said second material is selected from the group comprising silver, copper, aluminium, gold, tungsten, molybdenum, alumina, aluminium nitride, titanium carbide, silicon carbide, zirconium oxide, diamond, and graphite.